Active lava lakes as a window into magma and volcano dynamics
DESCRIPTION: The main objective of this project is to advance our understanding of circulation in magmatic conduits and the interaction and mass exchange between the subsurface magmatic system, the surface and the atmosphere. Of particular interest is the exchange of gasses such as CO2 and SO2. The investigators will address this target by examining lava lakes, the surface expression of magmatic conduits at open-vent volcanoes. Open-vent volcanoes are a primary locale for the exchange of materials between the Earth's interior and the surface. Conduits are complex systems, where degassing, cooling and crystallization take place. These processes lead to strong variability in buoyancy, thus causing convection, and in material properties, making flow behavior complicated. Lava lakes are rare, yet they are represented at all tectonic environments, as well as on other planets. Observations at lava lakes have already confirmed the existence of internal circulation in magmatic conduits, and this project aims to put better constraints on this dynamic phenomenon. Better understanding of the dynamics of lava lakes and open-vent conduits is key to constraining time and length scales for mass exchange rates between the Earth's interior, lava lake and atmosphere. The research team will address the connection between surface observations at lava lakes and models of degassing and convection at open-vent volcanic conduits, by analyzing large collections of visual and thermal data accumulated at three active lava lakes -Hawaii's Halemaumau crater, Mount Erebus (Antarctica), and Erta Ale(Africa). They will also employ video velocimetry on visible and thermal footage, extract detailed surface velocity fields of the convecting lakes, and quantify the time-dependent crustal plate configuration. Subsequently, they will search for correlations between the surface motions and other data sets collected simultaneously, including microseismicity and gas emission, to investigate the internal processes of degassing and overturns. A product of this work will be a high-quality set of observations of convection in a geologic system, against which numerical models could be benchmarked and tested. The measured velocity fields will be used as constraints for numerical forward models of the lakes. They plan to develop a numerical modeling framework capable of capturing the complex multi-phase systems, which lava and magma conduits are. The investigators will then use the computational fluid dynamics package OpenFOAM, an open-source, modular and flexible package, and allows for the integration of a wide range of physical processes. Specifically, they aim to develop a modeling framework that will build upon existing components of OpenFOAM: thermal convection with temperature-dependent rheology, gas-liquid two-phase flow, and solidification/melting. At every stage of the framework development, the investigators will examine the influence of internal parameters such as recharge events, conduit configuration and volatile content on their expression at the surface (plate motion and gas emission).